This invention relates generally to the audio field and more specifically to transmission of sound canceling audio with a sound beam.
Sound canceling techniques have become a growing application field with many systems designed to reduce sound in compartments such as automobile or aircraft cabins. However, such systems are designed to reduce the level of undesirable within a certain predetermined space by generating a sound canceling signal within the space. These methods do not attempt to cancel the sound generated at the sound source. Still another system has been designed to reduce sound generated by the sound source by actively quieting the sound source. See xe2x80x9cActive control of Sound radiation from a simply supported beam: Influence of bending near field wavesxe2x80x9d: C. Guirou, The Journal of the Acoustical Society of America, May 1993. What is needed is a method and apparatus capable of reducing sound at the source of the sound from a remote sound canceling source.
Furthermore, within an automobile compartment for example, sound canceling systems are designed to reduce the level of undesirable sound at a predetermined space, substantially around the occupant""s ears. However outside the space, the undesirable sound and the sound canceling signal may become additive, thereby increasing the total level of undesirable sound beyond the predetermined space. Thus, what is needed is a method and apparatus capable of directing sound canceling signal into the predetermined space while limiting the additive affect of the sound canceling signal with the undesirable sound signal beyond the predetermined space.